BackgroundMycoparasitism, a lifestyle where one fungus is parasitic on another fungus, has special relevance when the prey is a plant pathogen, providing a strategy for biological control of pests for plant protection. Probably, the most studied biocontrol agents are species of the genus Hypocrea/Trichoderma.ResultsHere we report an analysis of the genome sequences of the two biocontrol species Trichoderma atroviride (teleomorph Hypocrea atroviridis) and Trichoderma virens (formerly Gliocladium virens, teleomorph Hypocrea virens), and a comparison with Trichoderma reesei (teleomorph Hypocrea jecorina). These three Trichoderma species display a remarkable conservation of gene order (78 to 96%), and a lack of active mobile elements probably due to repeat-induced point mutation. Several gene families are expanded in the two mycoparasitic species relative to T. reesei or other ascomycetes, and are overrepresented in non-syntenic genome regions. A phylogenetic analysis shows that T. reesei and T. virens are derived relative to T. atroviride. The mycoparasitism-specific genes thus arose in a common Trichoderma ancestor but were subsequently lost in T. reesei.ConclusionsThe data offer a better understanding of mycoparasitism, and thus enforce the development of improved biocontrol strains for efficient and environmentally friendly protection of plants.

The asymmetric localization of mRNA plays an important role in coordinating posttranscriptional events in eukaryotic cells. We investigated the peripheral mitochondrial localization of nuclear-encoded mRNAs (MLR) in various conditions in which the mRNA binding protein context and the translation efficiency were altered. We identified Puf3p, a Pumilio family RNA-binding protein, as the first trans-acting factor controlling the MLR phenomenon. This allowed the characterization of two classes of genes whose mRNAs are translated to the vicinity of mitochondria. Class I mRNAs (256 genes) have a Puf3p binding motif in their 3'UTR region and many of them have their MLR properties deeply affected by PUF3 deletion. Conversely, mutations in the Puf3p binding motif alter the mitochondrial localization of BCS1 mRNA. Class II mRNAs (224 genes) have no Puf3p binding site and their asymmetric localization is not affected by the absence of PUF3. In agreement with a co-translational import process, we observed that the presence of puromycin loosens the interactions between most of the MLR-mRNAs and mitochondria. Unexpectedly, cycloheximide, supposed to solidify translational complexes, turned out to destabilize a class of mRNA-mitochondria interactions. Classes I and II mRNAs, which are therefore transported to the mitochondria through different pathways, correlated with different functional modules. Indeed, Class I genes code principally for the assembly factors of respiratory chain complexes and the mitochondrial translation machinery (ribosomes and translation regulators). Class II genes encode proteins of the respiratory chain or proteins involved in metabolic pathways. Thus, MLR, which is intimately linked to translation control, and the activity of mRNA-binding proteins like Puf3p, may provide the conditions for a fine spatiotemporal control of mitochondrial protein import and mitochondrial protein complex assembly. This work therefore provides new openings for the global study of mitochondria biogenesis.

During the 1980s, indications for the existence of intramembrane interactions between different G protein-coupled receptors, mainly between neuropeptide and monoamine receptors, were obtained in several brain areas (1, 2). It was later proposed that a possible molecular mechanism for this phenomenon was receptor heteromerization (3) and direct evidence for homo-and heteromerization of G protein-coupled receptors has been obtained by several groups. It was first shown that serotonin 5-HT-1B receptors exist as monomers and dimers (4). This was followed by demonstration of dimers and oligomers of dopamine D 1 and D 2 receptors (D 1 and D 2 R) in transfected Sf cells (5-7) and of adenosine A 1 receptors (A 1 Rs) in a natural cell line and in mammalian brain (8). It has recently been reported that a fully functional ␥-aminobutyric acid (GABA) type B receptor demands the heterodimerization of GABA B R1 and GABA B R2 receptors (9-12). Moreover, two functional opioid receptors, the and ␦ subtypes, can undergo heteromerization, which changes the pharmacology of the individual receptors and potentiates signal transduction (13). Finally, D 2 R and somatostatin receptor subtype 5 have been shown to physically interact by forming heterooligomers with enhanced functional activity (14). Direct protein-protein coupling can also exist between G proteincoupled anion channel receptors, as recently shown for dopamine D5 receptor and GABA A receptor, making possible bilateral inhibitory interactions between these receptors (15).Antagonistic adenosine͞dopamine interactions have been widely reported in the central nervous system in behavioral and biochemical studies. Furthermore, in animal models, adenosine agonists and antagonists are potent atypical neuroleptics and antiparkinsonian drugs, respectively (16-18). Thus, adenosine agonists inhibit and adenosine antagonists, such as caffeine, potentiate the behavioral effects induced by dopamine agonists. The evidence suggests that this antagonism is at least in part caused by an intramembrane interaction between specific subtypes of dopamine and adenosine receptors, namely, between